1. Field of the Invention
The invention relates in general to pushbuttons, and more specifically to pushbuttons illuminated with a solid state light source such as light emitting diodes (LED's).
2. Description of the Prior Art
Co-pending application Ser. No. 941,617, filed Sept. 12, 1978, in the name of F. E. Coyle, entitled "Pushbutton Assembly", which is assigned to the same assignee as the present application, discloses a new and improved pushbutton assembly suitable for use as a call button in an elevator system. Elevator pushbuttons, such as those used as an elevator call button in an elevator car, and elevator hall call buttons in the hall ways of a building, are subjected to constant usage by the public and thus must be built to withstand intense service. They're also subjected to considerable abuse, both intentional and unintentional. Thus, they must be constructed such that they do not invite vandalism. Further, they must be constructed to withstand abuse and vandalism, such as by being able to withstand actuation by an umbrella point, and extreme closing pressures, without external or internal damage.
Elevator pushbuttons must notify the sighted population that a call has been entered, by illuminating a predetermined portion of the pushbutton after actuation, and the illumination must be maintained until the call is answered. It would also be desirable to construct elevator pushbuttons such that they may be easily used by the visually handicapped.
In addition to reducing the number of service calls by constructing the pushbuttons to withstand high usage, abuse, and vandalism, they should be constructed to be easily and quickly serviced when service is necessary. For example, the light source in the pushbutton, or any other element of the pushbutton, must be easily and quickly replaceable by authorized personnel without the use of special tools.
Elevator systems are currently constructed with conventional electromechanical relays in the control, with low voltage solid state devices, or with a combination of the two. It would be desirable to construct the elevator pushbuttons in a modular manner such that they are assembled from completely interchangeable "building blocks", enabling high voltage light sources, such as neon lamps to be used, or low voltage solid state light sources, such as LEDs.
Regardless of the light source utilized, the resulting pushbutton structure must provide adequate illumination when actuated, to notify the user the call has been placed.
The hereinbefore mentioned co-pending application sets forth a new and improved pushbutton assembly which includes two basic sub-assemblies, a housing sub-assembly which carries the legend blocks to be illuminated, and an actuating plunger; and, a cover sub-assembly which carries the electrical contact assembly and the illuminating means. Assembly of the cover assembly with the housing assembly automatically aligns and operatively couples the actuating plunger with the electrical contact assembly, and it also automatically aligns the illuminating means with the legend blocks.
The illuminating means of the co-pending application may be any suitable light source, such as incandescent, neon, or solid state, such as LEDs.
It would be desirable to provide a new and improved solid state lighting arrangement suitable for use with certain of the components disclosed in the hereinbefore mentioned co-pending application. The new and improved solid state lighting arrangement must be compatible with the modular concept of this pushbutton system, it must adequately illuminate the legend blocks of the housing subassembly, it must be simple and rugged, in order to be consistent with the demanding requirements of elevator related pushbuttons, and it must be economically attractive.